The present invention relates to toe angle adjustment mechanisms that facilitate toe-in and toe-out adjustment of vehicle wheels.
There are industrial vehicles that employ a full hydraulic pressure system (FHPS) type rear axle. As shown in FIGS. 5(a) and 5(b), a typical FHPS type rear axle includes a rear axle beam 1. A wheel 2 is coupled to each end of the axle beam 1. A cylinder 5 is fixed longitudinally to the middle of the axle beam 1. A piston rod 4 extends outward from each end of the cylinder 5. The projection and retraction of the piston rod 4 turns each wheel 2 about an axis extending in a substantially vertical direction. This steers the vehicle.
Each wheel 2 is coupled to the axle beam 1 by means of a steering knuckle 3. When the wheel 2 is turned, the steering knuckle 3 is turned accordingly. The steering knuckle 3 is connected to the piston rod 4 by means of a rod end 7, which is secured to the distal end of the piston rod 4, a tie rod 18, and a ball joint.
The cylinder 5 is actuated by hydraulic pressure. The hydraulic pressure is applied by a steering valve, or ORBITROL, located below a steering wheel (not shown), which is arranged in front of the driver's seat. A nut portion 7a is provided on each rod end 7. The rod end 7 is threaded into the piston rod 4. The length of the piston rod 4 is adjusted by rotating the nut portion 7a.
When the steering wheel is at a neutral position, the vehicle moves straight. However, dimensional tolerances that are allowed when assembling the rear axle may cause the left and right wheels to aim in a direction that is not straight forward. This may result in side slipping.
To maintain the amount of side slipping within an allowable range, the nut portion 7a of each rod end 7 is turned to adjust the length of the piston rod 4. However, each rod end 7 must be rotated independently when turning the nut portion 7a. Thus, the rod end 7 must be disconnected from the associated tie rod 18 for adjustment. The rod end 7 and the tie rod 18 are reconnected after adjustment. Furthermore, exclusive tools are required to rotate the rod end 7. Thus, adjustment of the length of the piston rod 4 has been costly and inefficient.
Furthermore, the employment of a threaded adjusting mechanism together with a ball joint increases the size of the rod ends 7. This also results in cost increases.